Try what AlHuneke said with a flashlight to see if the problem is the backlight. If you don't see anything, open the laptop, check to see if the connectors are properly connected, also you can try to unplug and plug them back. The connector on the display and the one on the motherboard.
I reluctantly disagree with the prior post (sorry). Opening the laptop is asking for more trouble unless you know what you are doing. Try to get your hands on the service manual for the laptop and follow it. It is especially important to follow the ESD precautions. Most of the you tube videos are posted by idiots. There is not an electronics factory in the world that doesn't treat ESD very carefully.